A difficulty arises with the operation of shades for windows, doors and the like. In particular, shade systems include shade rolls to which the shade is attached. The shade is rolled onto the shade roll and dispensed from the roll and taken up by the roll as required. A major difficulty is caused by the requirements to keep the shade system small enough to not be obtrusive and to fit in the window or door space while still enabling the easy operation and movement of the shade. Motors are utilized to assist the movement of the shade but the weight of the shade can require very large, noisy motors.
Prior art devices abound that provide assistance to motors and to the operation of shade systems. In particular, roll type shades, curtains, and doors can be counterbalanced as has been known in the art. In Erpenbeck, U.S. Pat. No. 4,009,745, a window shade support roller having an improved spring motor construction and method of manufacture includes a spring retaining structure which holds a driving spring and a spear structure having an integral spear. The spear structure and the spring retaining structure cooperate together, and with a ball, to form a ball clutch mechanism. The spring retaining structure has ball-receiving recesses with canting floors which simplify assembly. Assembly steps include inserting balls into the spring retaining structure, inserting the spear structure into the spring retaining structure, inserting a dowel into the spear structure, positioning a spring around the dowel, and inserting one end of such spring between portions of the spring retaining structure, which uniquely capture and retain the end without other securement, for torsional winding of the spring. However this device must be mounted horizontally so gravity can move the balls in the channel of the ratchet surface arrangement. If the device is mounted vertically, such that there is no force from gravity the balls will not move in the channel.
In U.S. Pat. Nos. 6,283,192 and 6,957,683 to Toti, a spring drive system for window covers is disclosed which includes a so-called flat spring drive and the combination whose elements are selected from a group which includes (1) a band transmission which provides varying ratio power transfer as the cover is opened and closed; (2) a gear system selected from various gear sets which provide frictional holding force and fixed power transfer ratios; and (3) a gear transmission which provides fixed ratio power transfer as the cover is opened or closed. The combination permits the spring drive force at the cover to be tailored to the weight and/or compression characteristics of the window cover such as a horizontal slat or pleated or box blind as the cover is opened and closed. This art discusses the use of multiple drums with flat type springs but does not address the issue of possible back winding the spring.
In U.S. Pat. No. 6,648,050 to Toti, a spring drive system useful for window covers is disclosed, which comprises one or more coil spring drives or flat spring drives and the combination whose elements are selected from one or more of a group which includes (1) a band or cord transmission which provides varying ratio power transfer as the cover is opened and closed; (2) gear means comprising various gear sets which provide frictional holding force and fixed power transfer ratios; (3) a gear transmission which provides fixed ratio power transfer as the cover is opened or closed; (4) crank mechanisms; (5) brake mechanisms; and (6) recoiler mechanisms. The combination permits the spring drive force to be tailored to the weight and/or compression characteristics of an associated window cover such as a horizontal slat or pleated or box blind as the cover is opened and closed.
In U.S. Pat. No. 6,659,156 to Wen et al., a screw transmission mechanism for a motor-driven blind is constructed to include a driving unit, and at least one cord roll-up unit controlled by the driving unit to lift/lower or tilt the slats of the motor-driven Venetian blind. Each cord roll-up unit includes an amplitude modulation set controlled by the driving unit to lift/lower the slats and bottom rail of the Venetian blind, a frequency modulation set for rotation with the amplitude modulation set to tilt the slats of the Venetian blind, and a linkage adapted to control connection between the frequency modulation set and the amplitude modulation set.
In U.S. Pat. No. 6,854,503 to Cross et al., the invention includes an unbalanced horizontal blind with a spring means to provide a lifting or retraction force for the slats of the blinds. A brake means prevents undesired movement of the slats that would otherwise result from the continuous retraction force of the spring means when the slats are set in a desired position. Controls for the release of the brake means and tilting are also provided in an embodiment of a blind of the invention. An embodiment of the invention permits the blind to be operated by a single wand that can be used to either raise the slats or tilt the slats. This eliminates the need for a loose cord or bead chain that would traditionally be used as the user interface for controlling the movement of the slats of the blind.
Despite these efforts, the art is still missing a counter balancing system that is easily adjustable such that counter balances may be added or deleted as the circumstances require and as they change. That is, all the prior art of which applicants are aware are fixed systems or complex adjustable systems that are bulky and hard to manipulate. At best prior art systems can accommodate small adjustments but major changes in the weight of the shade to be moved require total replacement of existing counter balances.
Another missing element in the prior art is a simple system for the prevention of back winding of the counter balance springs. For example, if some element of a prior art system was changed, like a battery or batteries, and then the shade was rehung partially deployed, this can result in a reverse wind of the counter balance spring when the motor moves the shade up to the fully open position. This is not desirable since it can, and often does, damage the counter balance systems in the prior art.
Thus, it is an object of this invention to provide a counter balance system and method that is modular and that is easy to install and adjust. Further it is an objective of the invention to provide a counter balance system that does not back wind and can not back wind during operation of a shade system.